Practice Quiz Chapter 8 Torque

Practice Quiz Ch 8
1) A 15.0-kg child is sitting on a playground teeter-totter, 1.50 m from the pivot. What force, applied 0.300 m on the other side of the pivot, is needed to make the child lift off the ground?
A) 75.0 N
B) 736 N
C) 44.1 N
D) 66.2 N
Answer: B
2) A man is holding an 8.00-kg vacuum cleaner at arm's length, a distance of 0.550 m from his shoulder. What is the torque on the shoulder joint if the arm is held at 30.0° below the horizontal?
A) 21.6 Nm
B) 2.20 Nm
C) 12.6 Nm
D) 37.4 Nm
Answer: D
3) An 82.0-kg diver stands at the edge of a light 5.00-m diving board, which is supported by two pillars 1.60 m apart, as shown in Figure 11-1. Find the force exerted by pillar A.
A) 1.71 kN downwards
B) 1.71 kN upwards
C) 2.51 kN downwards
D) 2.51 kN upwards
Answer: A
4) A uniform meter stick with a mass of 135 g rotates about an axis perpendicular to the stick passing through the center of the stick with an angular speed of 3.50 rad/s2. What is the magnitude of the angular momentum of the stick?
A) 0.0394 kg•m2/s
B) 0.473 kg•m2/s
C) 0.158 kg•m2/s
D) 0.0236 kg•m2/s
Answer: A
5) The L-shaped object shown in Figure 11-6 consists of the masses connected by light rods. How much work must be done to accelerate the object from rest to an angular speed of 3.25 rad/s about the y-axis?
A) 374 J
B) 173 J
C) 42.2 J
D) 27.4 J
Answer: B
6) When you ride a bicycle, in what direction is the angular velocity of the wheels?
A) to your left
B) to your right
C) forwards
D) backwards
Answer: A
7) The rotating systems shown in the figure differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right).
If you release the hanging blocks simultaneously from rest,
A) the block at left lands first.
B) the block at right lands first.
C) both blocks land at the same time.
D) it is impossible to tell which block reaches the bottom first.
Answer: B